With the rapid development of broadband services, users' demand for access network bandwidth has greatly increased. passive optical network (PON) is an important means for user access at present. As shown in FIG. 1, in the existing PON system structure, the local optical line terminal (OLT) is connected to an optical splitter through trunk optical fibers, the optical splitter is connected to multiple user optical network units (ONU) through branch optical fibers, and the OLT and ONUs communicate through a pair of wavelengths.
At present, the OLT can use multi-wavelength optical modules to configure four or more uplink and downlink wavelengths. For a scenario where the OLT supports multiple wavelengths, as shown in FIG. 2, in a downlink direction, multiple different wavelengths λd0, λd1 . . . λdn are transmitted to an optical wavelength distribution network (OWDN) after combining at OLT and allocated to each ONU according to different wavelengths. In an uplink direction, different users ONU transmit different optical wavelengths λu0, λu1 . . . λun to OWDN for combining and then transmit the optical wavelengths to OLT. In this way, the uplink and downlink transmission of the optical signal is completed. The downlink wavelength λdi (i=0, 1, . . . n) and the uplink wavelength λui (i=0, 1, . . . n) can work in the same band or in different bands.
As can be seen from FIG. 2, in order to adapt to the OLT supporting multiple wavelengths, the user side needs to deploy a corresponding number of ONUs supporting single wavelengths to correspond to each wavelength respectively. In addition, the ONU can adjust the working downlink wavelength λdi (i=0, 1, . . . n) and uplink wavelength λui (i=0, 1, . . . n) as needed with the cooperation of the OLT. With the development of network and service, ONU needs to support more throughput and bandwidth. The number of wavelengths supported by ONU has gradually grown from one to multiple, and the wavelengths supported by ONU are also flexible and changeable. There is no relevant scheme for achieving ONU supporting different numbers of wavelengths and different wavelengths under the same ODN and making full use of bandwidth.